This invention relates to a brake disk for disk brakes and more particularly a wheel brake disk for rail vehicles. These disk brakes includes a friction ring which can be acted upon on one side by at least one brake shoe. The friction ring has at least two ring segments held on a supporting body and connecting elements which connect the opposite ends of the ring segments at the juncture of the ring segments and exclude at least radial relative displacements of the ring segments.
Many brake disks of this type are known which are constructed as divided wheel brake disks, and the supporting body is often the wheel disk of a rail vehicle wheel. A brake disk of this type is known, for example, from FIG. 4 of German Patent Document DE-B 21 33 235 or Great Britain Patent 1,359,388. The two ring segments of the friction ring are held on the wheel disk by fasteners of screws and clamping sleeves which are parallel to the axis of rotation. The juncture of the ring segments, which have an air gap, are bridged by tangential bolts constructed as the connecting elements. The ends of the bolts are in corresponding pocket bores on the faces of the ring segments. In the case of high rotational speeds of the wheel, the centrifugal forces affecting the friction ring or its ring segment attempt to expand this ring or these segments, particularly at the weak points caused by the juncture. Because of their tangential alignment, the bolt which bridge the juncture are incapable of preventing such expansions. While the bolts protrude partially from the pocket bores, the air gaps at the juncture may in this case when in an undesirable manner.
Wheel disk brakes of the above-mentioned type are also known in which, instead of the above-described bolts, tangentially aligned screwed connections are the connecting elements between the ring segments. However, such screwed connections require a relatively large amount of space. They can therefore only be implemented when the friction rings are constructed in a vented manner. That is, when they are equipped with radial cooling ribs on their side facing away from the brake shoe, or when a sufficient amount of space for these screwed connections exists on the rear of the friction rings. These types of screwed connections cannot be arranged in the case of unvented friction rings or friction rings having only short cooling ribs.
It is also known to provide semi-cylindrical recesses in the mutually opposite faces of divided friction the ring segments, respective mutually opposite. A cylindrical or circular-disk-shaped body is inserted in the recess to support the respective adjacent ring segments mutually as well as in the circumferential direction with respect to one another and also to prevent radial relative displacements. Reference is made for this purpose to German Patent Documents DE-B 22 30 805 and 24 47 555 and to German Patent Document DE-OS 26 20 623 corresponding to U.S. Pat. Nos. 3,804,213; 3,902,578 and 4,004,661 respectively.
It is an object of the invention to further develop a segmental friction ring brake disk by simple devices that prevents expansion of the juncture between the two ring segments under the occurrence of high centrifugal forces or other forces, prevents relative radial displacements and virtually no additional space is required for the connecting elements so that the brake disk can also be constructed in an unvented manner or with only short cooling ribs.
According to the invention, this object is achieved in that the friction ring has, on at least one side, ring grooves which are open to this side and bridge the juncture of the ring segments. The axes of these ring grooves extend parallel to the axis of the friction ring and their depth is less than the axial width of the ring segments. A ring body is inserted into each ring groove and bridges the juncture. Preferably, the ring body fills the ring groove.
This construction of the brake disk provides a connection at the juncture between the ring segments which can be stressed not only with respect to pressure forces, shearing forces and radial displacement forces, but the connection can also absorb tensile forces. As a result, the adjacent ring segments obtain a fixed but flexible connection to one another such that their fastener device on the supporting body is relieved of certain stress components, such as stress caused by centrifugal force, and can therefore be dimensioned to be correspondingly weaker and smaller. It is important that, by the ring bodies connecting the ring segments, temperature-caused deviations of the ring segments from their circle-segment-shaped desired design are not hindered because the connecting elements formed by the ring bodies act as joints which permit, to a limited extent, relative rotating movements of the faces of the ring segments, which are opposite one another in the juncture, about the axis of the ring bodies.